(180c) Investigation of burning mode for diesel particulate oxidation: contrasting O2 and NO2
The physical characteristics of diesel particulates from conventional diesel, biodiesel and
blends of the two were investigated at several points along the O2 and NO2 oxidation reactions. BET measurements elucidated the surface area evolution with extent of oxidation for the two oxidizers and revealed differences in surface area evolution in the samples when oxidized with O2. Particulate matter from biodiesel initially has greater surface area than particulate from ULSD, an advantage, which is maintained under O2 oxidation until approximately 40% of the sample has been consumed. HR -TEM and fringe analysis confirm that initial differences in the lamella lengths have disappeared by 40% burnout of the samples. TEM images suggest that surface area evolves mostly internally for O2 oxidation as the primary particle diameters do not follow the shrinking core trajectory. However, for NO2 there are no sample-specific dependencies in either reactivity and surface area. TEM images
suggest that NO2 oxidation occurs by a mostly external trajectory.